Colored data storage media

ABSTRACT

One method for producing a data storage media, comprises: molding a material comprising plastic and a fluorescent material to form a substrate, and disposing a data layer on the substrate. The substrate has a transmissivity of about 85% or less at a readback laser wavelength when traversing a 1.2 mm thick colored substrate, and the has a fluorescent color emission wavelength which is not equal to the readback laser wavelength.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. application Ser. No.09/766,303, filed on Jan. 19, 2001, which claims the benefit of thefiling date of U.S. Provisional Application Serial No. 60/166,135, filedon Sep. 29, 2000, which is hereby incorporated by reference.

BACKGROUND OF INVENTION

[0002] Optical, magnetic and magneto-optic media are primary sources ofhigh performance storage technology which enables high storage capacitycoupled with a reasonable price per megabyte of storage. Use of opticalmedia has become widespread in audio, video, and computer dataapplications in such formats as compact disk (CD), digital versatiledisk (DVD) including multi-layer structures like DVD-5, DVD-9, andmulti-sided formats such as DVD-10, and DVD-18, magneto-optical disk(MO), and other write-once and rewritable formats such as CD-R, CD-RW,DVD-R, DVD-RW, DVD+RW, DVD-RAM. In these and other formats, data areencoded onto a substrate into a digital data series. In pre-recordedmedia, such as CD, the data are typically pits and grooves formed on thesurface of a plastic substrate through a method such as injectionmolding, stamping or the like.

[0003] In recordable and rewritable media, the data are encoded bylaser, which illuminates an active data layer that undergoes a phasechange, thus producing a series of highly-reflecting or non-reflectiveregions making up the data stream. In these formats, a laser beam firsttravels through a plastic substrate before reaching the data layer. Atthe data layer, the beam is either reflected or not, in accordance withthe endcoded data. The laser light then travels back through the plasticand into an optical detector system where the data are interpreted.

[0004] It is well known in the art that, due to the sensitivity of theoptical readout system, the amount of absorption of the light by themedia should be minimized. Consequently, the plastic in the opticalmedia is a colorless, transparent material having good birefringenceproperties, such as polycarbonate. Although media formats have beenintroduced which read data from the top-side of a substrate, the vastmajority of playback systems are only compatible with media requiringthe laser to travel through the substrate twice. Hence, the transparencyto the laser is a requirement and colorless materials are typically usedto maximize transparency at the laser wavelength.

[0005] The widespread use of colorless, transparent materials makesproduct differentiation difficult, except by costly printing methods onthe top surface of the optical media. Furthermore, in the cases whereprinted decorations cover one entire surface of a disk, the coveredsurface is unusable for data storage.

[0006] What is needed in the art are colored plastic compositions foruse as optical media.

TECHNICAL FIELD

[0007] The present disclosure relates to data storage media, andespecially relates to fluorescent, plastic data storage media.

SUMMARY OF INVENTION

[0008] The colored data storage media overcomes the above describeddrawbacks and deficiencies. One method for producing a data storagemedia, comprises: molding a material comprising plastic and afluorescent material to form a substrate, and disposing a data layer onthe substrate. The substrate has a transmissivity of about 85% or lessat a readback laser wavelength when traversing a 1.2 mm thick coloredsubstrate, and the has a fluorescent color emission wavelength which isnot equal to the readback laser wavelength.

[0009] Another method for producing a data storage media comprises:molding a material comprising plastic and colorant to form a substrate,wherein the substrate has a transmissivity of about 70% to about 85% ata readback laser wavelength when traversing a 1.2 mm thick coloredsubstrate, and disposing a data layer on the substrate.

[0010] Yet another method for producing the data storage media,comprises: molding a material comprising plastic, and a fluorescentmaterial to form a substrate, wherein the substrate has a transmissivityof about 85% or less at a readback laser wavelength when traversing a1.2 mm thick colored substrate, and wherein the substrate has afluorescent color emission wavelength which is not equal to the readbacklaser wavelength and has a transmissivity of about 70% to about 90% atthe laser readback wavelength, and disposing a data layer on thesubstrate.

[0011] Another method for producing data storage media, comprises:molding a material comprising plastic, colorant, and visual effects toform a substrate, and disposing a data layer on the substrate. Thesubstrate has a transmissivity of about 85% or less at a readback laserwavelength when traversing a 1.2 mm thick colored substrate, and thevisual effects are selected from the group consisting of glass, metal,titanium dioxide, mica, angular metamerism materials, and combinationscomprising at least one of the foregoing visual effects.

DETAILED DESCRIPTION

[0012] The present invention relates to data storage media, namely,colored optical data storage media and methods for making the same. Inone embodiment, the colored media has, at the readback laser wavelength,a transmissivity of light of about 85% or less, with about 70% to about85% preferred, about 75% to about 80% also preferred, and about 75% toabout 85% especially preferred, when traversing a 1.2 mm thick coloredsubstrate (disk). Alternatively, if fluorescent, the media preferablyemits light at a wavelength which does not inhibit data retrieval. Thefluorescent media can comprise a substrate which has a transmissivity,at the readback laser wavelength, of about 85% or less, preferablyexceeding 68%, with about 70% to about 95% preferred, about 70% to about90% more preferred, and about 70% to about 85% especially preferred,when traversing a 1.2 mm thick substrate (disk).

[0013] Typically, these storage media can comprise a substratecomprising a plastic and a colorant which does not inhibit dataretrieval. Generally, up to about 10 weight percent (wt %) colorant canbe used, with up to about 5 wt % preferred, up to about 1 wt % colorantmore preferred, and less than about 0.5 wt % or so colorant especiallypreferred, based upon the total weight of the substrate.

[0014] In theory, any plastic that exhibits appropriate properties andcan be employed. However, the plastic should be capable of withstandingthe subsequent processing parameters (e.g., application of subsequentlayers) such as sputtering (i.e., temperatures up to and exceeding about200° C. (typically up to or exceeding about 300° C.) for magnetic media,and temperatures of about room temperature (about 25° C.) up to about150° C. for magneto-optic media). That is, it is desirable for theplastic to have sufficient thermal stability to prevent deformationduring the deposition steps. For magnetic media, appropriate plasticsinclude thermoplastics with glass transition temperatures greater thanabout 150° C., with greater than about 200° C. preferred (e.g.,polyetherimides, polyetheretherketones, polysulfones, polyethersulfones,polyetherethersulfones, polyphenylene ethers, polyimides, high heatpolycarbonates, etc.); with materials having glass transitiontemperatures greater than about 250° C. more preferred, such aspolyetherimide in which sulfonedianiline or oxydianiline has beensubstituted for m-phenylenediamine, among others, as well as polyimides,such as Probimide (or the dry powder equivalent, Matrimid 5218, fromCiba Geigy Chemical); combinations comprising at least one of theforegoing plastics, and others.

[0015] Additionally, it is possible for thermosets to be used in theapplication provided the thermoset possess sufficient flow under thestamping conditions to permit formation of the desired surface features.As various applications may require polymers with different glasstransition temperatures, it may be advantageous to be able to adjust theglass transition temperature of a plastic (homopolymer, copolymer, orblend) to achieve a film with the desired glass transition temperature.To this end, polymer blends, such as those described in U.S. Pat. No.5,534,602 (to Lupinski and Cole, 1996), may be employed in thepreparation of the coating solution. In this example, polymer blendsprovide, selectively, variable glass transition temperatures of about190° C. to about 320° C.

[0016] Some possible examples of plastics include, but are not limitedto, amorphous, crystalline and semi-crystalline thermoplastic materials:polyvinyl chloride, polyolefins (including, but not limited to, linearand cyclic polyolefins and including polyethylene, chlorinatedpolyethylene, polypropylene, and the like), polyesters (including, butnot limited to, polyethylene terephthalate, polybutylene terephthalate,polycyclohexylmethylene terephthalate, and the like), polyamides,polysulfones (including, but not limited to, hydrogenated polysulfones,and the like), polyimides, polyether imides, polyether sulfones,polyphenylene sulfides, polyether ketones, polyether ether ketones, ABSresins, polystyrenes (including, but not limited to, hydrogenatedpolystyrenes, syndiotactic and atactic polystyrenes, polycyclohexylethylene, styrene-co-acrylonitrile, styrene-co-maleic anhydride, and thelike), polybutadiene, polyacrylates (including, but not limited to,polymethylmethacrylate, methyl methacrylate-polyimide copolymers, andthe like), polyacrylonitrile, polyacetals, polycarbonates, polyphenyleneethers (including, but not limited to, those derived from2,6-dimethylphenol and copolymers with 2,3,6-trimethylphenol, and thelike), ethylene-vinyl acetate copolymers, polyvinyl acetate, liquidcrystal polymers, ethylene-tetrafluoroethylene copolymer, aromaticpolyesters, polyvinyl fluoride, polyvinylidene fluoride, polyvinylidenechloride, Teflons, as well as thermosetting resins such as epoxy,phenolic, alkyds, polyester, polyimide, polyurethane, mineral filledsilicone, bis-maleimides, cyanate esters, vinyl, and benzocyclobuteneresins, in addition to blends, copolymers, mixtures, reaction productsand composites comprising at least one of the foregoing plastics.

[0017] As used herein, the terms “polycarbonate”, “polycarbonatecomposition”, and “composition comprising aromatic carbonate chainunits” includes compositions having structural units of the formula (I):

[0018]

[0019] in which at least about 60 percent of the total number of R¹groups are aromatic organic radicals and the balance thereof arealiphatic, alicyclic, or aromatic radicals.

[0020] Preferably, R¹ is an aromatic organic radical and, morepreferably, a radical of the formula (II):

—Λ¹—Y¹—Λ²—  (II)

[0021] wherein each of A¹ and A² is a monocyclic divalent aryl radicaland Y¹ is a bridging radical having one or two atoms which separate A¹from A². In an exemplary embodiment, one atom separates A¹ from A².Illustrative, non-limiting examples of radicals of this type are —O—,—S—, —S(O)—, —S(O₂)—, —C(O)—, methylene, cyclohexyl-methylene,2-[2,2,1]-bicycloheptylidene, ethylidene, isopropylidene,neopentylidene, cyclohexylidene, cyclopentadecylidene,cyclododecylidene, and adamantylidene. The bridging radical Y¹ can be ahydrocarbon group or a saturated hydrocarbon group such as methylene,cyclohexylidene or isopropylidene.

[0022] Polycarbonates can be produced by the interfacial reaction ofdihydroxy compounds in which only one atom separates A¹ and A². As usedherein, the term “dihydroxy compound” includes, for example, bisphenolcompounds having general formula (III) as follows:

[0023] wherein R^(a) and R^(b) each represent a halogen atom or amonovalent hydrocarbon group and may be the same or different; p and qare each independently integers from 0 to 4; and X^(a) represents one ofthe groups of formula (IV):

[0024] wherein R^(a) and R^(b) each independently represent a hydrogenatom or a monovalent linear or cyclic hydrocarbon group and R^(e) is adivalent hydrocarbon group.

[0025] Some illustrative, non-limiting examples of suitable dihydroxycompounds include dihydric phenols and the dihydroxy-substitutedaromatic hydrocarbons disclosed by name or formula (generic or specific)in U.S. Pat. No. 4,217,438, which is incorporated herein by reference. Anonexclusive list of specific examples of the types of bisphenolcompounds that may be represented by formula (III) includes thefollowing: 1,1-bis(4-hydroxyphenyl) methane; 1,1-bis(4-hydroxyphenyl)ethane; 2,2-bis(4-hydroxyphenyl) propane (hereinafter “bisphenol A” or“BPA”); 2,2-bis(4-hydroxyphenyl) butane; 2,2-bis(4-hydroxyphenyl)octane; 1,1-bis(4-hydroxyphenyl) propane; 1,1-bis(4-hydroxyphenyl)n-butane; bis(4-hydroxyphenyl) phenylmethane;2,2-bis(4-hydroxy-1-methylphenyl) propane;1,1-bis(4-hydroxy-t-butylphenyl) propane; bis (hydroxyaryl) alkanes suchas 2,2-bis(4-hydroxy-3-bromophenyl) propane; 1,1-bis (4-hydroxyphenyl)cyclopentane; and bis(hydroxyaryl) cycloalkanes such as1,1-bis(4-hydroxyphenyl) cyclohexane; and the like as well ascombinations comprising at least one of the foregoing.

[0026] It is also possible to employ polycarbonates resulting from thepolymerization of two or more different dihydric phenols or a copolymerof a dihydric phenol with a glycol or with a hydroxy- or acid-terminatedpolyester or with a dibasic acid or with a hydroxy acid or with analiphatic diacid in the event a carbonate copolymer rather than ahomopolymer is desired for use. Generally, useful aliphatic diacids havefrom 2 to about 40 carbons. A preferred aliphatic diacid is dodecandioicacid. Polyarylates and polyester-carbonate resins or their blends canalso be employed. Branched polycarbonates are also useful, as well asblends of linear polycarbonate and a branched polycarbonate. Thebranched polycarbonates may be prepared by adding a branching agentduring polymerization.

[0027] These branching agents are well known and may comprisepolyfunctional organic compounds containing at least three functionalgroups which may be hydroxyl, carboxyl, carboxylic anhydride, haloformyland mixtures comprising at least one of the foregoing. Specific examplesinclude trimellitic acid, trimellitic anhydride, trimellitictrichloride, tris-p-hydroxy phenyl ethane, isatin-bis-phenol,tris-phenol TC (1,3,5-tris((p-hydroxyphenyl)isopropyl)benzene),tris-phenol PA (4(4(1,1-bis(p-hydroxyphenyl)-ethyl) alpha,alpha-dimethylbenzyl)phenol), 4-chloroformyl phthalic anhydride, trimesic acid andbenzophenone tetracarboxylic acid, and the like. The branching agentsmay be added at a level of about 0.05 to about 2.0 weight percent.Branching agents and procedures for making branched polycarbonates aredescribed in U.S. Pat. Nos. 3,635,895 and 4,001,184 which areincorporated by reference. All types of polycarbonate end groups areherein contemplated.

[0028] Preferred polycarbonates are based on bisphenol A, in which eachof A¹ and A² is p-phenylene and Y¹ is isopropylidene. Preferably, theweight average molecular weight of the polycarbonate is about 5,000 toabout 100,000, more preferably about 10,000 to about 65,000, and mostpreferably about 15,000 to about 35,000.

[0029] In monitoring and evaluating polycarbonate synthesis, it is ofparticular interest to determine the concentration of Fries productpresent in the polycarbonate. As noted, the generation of significantFries product can lead to polymer branching, resulting in uncontrollablemelt behavior. As used herein, the terms “Fries” and “Fries product”denote a repeating unit in polycarbonate having the formula (V):

[0030] wherein X^(a) is a bivalent radical as described in connectionwith Formula (III) supra.

[0031] The polycarbonate composition may also include various additivesordinarily incorporated in resin compositions of this type. Suchadditives are, for example, fillers or reinforcing agents; heatstabilizers; antioxidants; light stabilizers; plasticizers; antistaticagents; mold releasing agents; additional resins; blowing agents; andthe like, as well as combinations comprising at least one of theforegoing additives. Examples of fillers or reinforcing agents includeglass fibers, asbestos, carbon fibers, silica, talc and calciumcarbonate. Examples of heat stabilizers include triphenyl phosphite,tris-(2,6-dimethylphenyl)phosphite, tris-(mixed mono-anddi-nonylphenyl)phosphite, dimethylbenene phosphonate and trimethylphosphate. Examples of antioxidants includeoctadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, andpentaerythrityl-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. Examples of light stabilizers include2-(2-hydroxy-5-methylphenyl) benzotriazole,2-(2-hydroxy-5-tert-octylphenyl)-benzotriazole and 2-hydroxy-4-n-octoxybenzophenone. Examples of plasticizers includedioctyl-4,5-epoxy-hexahydrophthalate,tris-(octoxycarbonylethyl)isocyanurate, tristearin and epoxidizedsoybean oil. Examples of the antistatic agent include glycerolmonostearate, sodium stearyl sulfonate, and sodiumdodecylbenzenesulfonate. Examples of mold releasing agents includestearyl stearate, beeswax, montan wax and paraffin wax. Examples ofother resins include but are not limited to polypropylene, polystyrene,polymethyl methacrylate, and polyphenylene oxide. Combinations of any ofthe foregoing additives may be used. Such additives may be mixed at asuitable time during the mixing of the components for forming thecomposition.

[0032] The color is imparted to the substrate with a colorant (e.g.,dye, pigment, or the like). The amount and type of colorant is chosen toavoid producing a substrate having contaminants (i.e., by-products)which produce data readout errors, and to attain the desired color,while controlling transmissivity, at the readback laser wavelength, togreater than about 68%, when traversing a 1.2 mm thick colored substrate(disk). Contrary to conventional belief, the substrate may befluorescent, that is, emit light at a particular wavelength. In thisembodiment, the colorant is a fluorescent material which has afluorescent color emission wavelength which is not equal to the readbacklaser wavelength, and preferably different by at least about 10nanometers (nm) (i.e., higher or lower) than the readback laserwavelength, with a difference of about 15 nm or greater preferred, andabout 20 nm or greater especially preferred. Here it is furtherpreferred that the substrate have a transmissivity at the readback laserfrequency, of greater than about 70% when traversing a 1.2 mm thickcolored substrate (disk).

[0033] Some possible fluorescent colorants include: [t1] DESCRIPTIONCOMPOSITION C.I. Pigment Red 181 benzothiophenone (C₁₈H₁₀Cl₂O₂S₂) C.I.Solvent Orange 63 14H-anthra{2.1.9-MNA}thioxanthen-14-one C.I. DisperseRed 364 2(3oxobenzothien2 (3H) yliden) benzothiophenone C.I. SolventBlue 97 anthraquinone 1,4-bis(2,6-diethyl-4-methlphenl)aminoanthracendione C.I. Solvent Green 53,9-perylendicarboxlic acid, bis-2- methylpropyl ester C.I. SolventYellow 98 2-octadecylthioxanthenoiso quinolinfionr

[0034] as well as other fluorescent colorants, and combinationscomprising at least one of the foregoing colorants.

[0035] Further color or design may be imparted to the substrate via adecorative layer which does not comprise an absorption percentagelimitation. The decorative layer, which is disposed on a side of thedisk opposite a data storage layer or in between data storage layerswhich are read from opposite sides of the disk, can be any color ordesign, such as a design which optionally includes sparkle, i.e., visualeffects which scatter the incident light (such as glass or metal (in theform of flakes, chips, particles, powder, and the like, as well ascombinations comprising at least one of the foregoing forms, with flakespreferred), titanium dioxide (TiO₂), mica, fiberglass, angularmetamerism materials such as, ChromaFlair Gold/Silver 080, ChromaFlairCyan/Purple 230 (commercially available from Flex Products, Santa Rosa,Calif.), among other materials, as well as combinations comprising atleast one of the foregoing visual effects.

[0036] In addition to the plastic and colorant, the composition mayoptionally include various additives ordinarily incorporated in resincompositions of this type. Such additives may include antioxidants, heatstabilizers, anti-static agents (tetra alkylammonium benzene sulfonatesalts, tetra alkylphosphonium benzene sulfonate salts, and the like),mold releasing agents (pentaerythritol tetrastearate; glycerolmonstearate, and the like), and the like, and combinations comprising atleast one of the foregoing. For example, the substrate can compriseabout 0.01 to about 0.1 wt % of a heat stabilizer; about 0.01 to about0.2 wt % of an antistatic agent; and about 0.1 to about 1 wt % of a moldreleasing agent; based upon the total weight of the substrate.

[0037] Some possible antioxidants include, for example,organophosphites, e.g., tris (nonyl-phenyl)phosphite,tris(2,4-di-t-butylphenyl)phosphite,bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite, distearylpentaerythritol diphosphite and the like; alkylated monophenols,polyphenols and alkylated reaction products of polyphenols with dienes,such as, for example,tetrakis[methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)] methane,3,5-di-tert-butyl-4-hydroxyhydrocinnamate octadecyl,2,4-di-tert-butylphenyl phosphite, and the like; butylated reactionproducts of para-cresol and dicyclopentadiene; alkylated hydroquinones;hydroxylated thiodiphenyl ethers; alkylidene-bisphenols; benzylcompounds; esters of beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionicacid with monohydric or polyhydric alcohols; esters ofbeta-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid withmonohydric or polyhydric alcohols; esters of thioalkyl or thioarylcompounds, such as, for example, distearylthiopropionate,dilaurylthiopropionate, ditridecylthiodipropionate, and the like; amidesof beta-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid; and thelike, as well as combinations comprising at least one of the foregoing.

[0038] Other potential additives which may be employed comprise: UVabsorbers; stabilizers such as light and thermal stabilizers (e.g.,acidic phosphorous-based compounds); hindered phenols; zinc oxide and/orzinc sulfide particles; lubricants (mineral oil, and the like),plasticizers, dyes (quinines, azobenzenes, and the like); among others,as well as combinations comprising at least one of the foregoingadditives.

[0039] In order to aide in the processing of the plastic, particularlypolycarbonate, catalyst(s) may also be employed, namely in the extruderor other mixing device. The catalyst typically assists in controllingthe viscosity of the resulting material. Possible catalysts includetetraalkylammonium hydroxide, tetraalkylphosphonium hydroxide and thelike, with diethyidimethylammonium hydroxide and tetrabutylphosphoniumhydroxide preferred. The catalyst(s) can be employed alone or incombination with quenchers such as acids, such as phosphoric acid, andthe like. Additionally, water may be injected into the polymer meltduring compounding and removed as water vapor through a vent to removeresidual volatile compounds.

[0040] Data storage media can be produced by first forming the plasticusing a conventional reaction vessel capable of adequately mixingvarious precursors, such as a single or twin screw extruder, kneader,blender, or the like. The precursors can either be premixed with thecolorant (e.g., in a pellet, powder, and/or liquid form) andsimultaneously fed through a hopper into the extruder, or the colorantcan be optionally added in the feed throat or through an alternateinjection port of the injection molding machine or other molding.

[0041] The extruder should be maintained at a sufficiently hightemperature to melt the plastic precursors without causing decompositionthereof. For polycarbonate, for example, temperatures of about 220° C.to about 360° C. can be used, with about 260° C. to about 320° C.preferred. Similarly, the residence time in the extruder should becontrolled to minimize decomposition. Residence times of up to about 2minutes (min) or more can be employed, with up to about 1.5 minpreferred, and up to about 1 min especially preferred. Prior toextrusion into the desired form (typically pellets, sheet, web, or thelike, the mixture can optionally be filtered, such as by melt filteringand/or the use of a screen pack, or the like, to remove undesirablecontaminants or decomposition products.

[0042] Once the plastic composition has been produced, it can be formedinto the data storage media using various molding and/or processingtechniques. Possible molding techniques include injection molding, filmcasting, extrusion, press molding, blow molding, stamping, and the like.Once the substrate has been produced, additional processing, such aselectroplating, coating techniques (spin coating, spray coating, vapordeposition, screen printing, painting, dipping, and the like),lamination, sputtering, and combinations comprising at least one of theforegoing processing techniques, among others conventionally known inthe art, may be employed to dispose desired layers on the coloredsubstrate.

[0043] An example of a polycarbonate data storage media comprises aninjection molded colored polycarbonate substrate which may optionallycomprise a hollow (bubbles, cavity, and the like) or filled (metal,plastics, glass, ceramic, and the like, in various forms such as fibers,spheres, particles, and the like) core. Disposed on the substrate arevarious layers including: a data layer, dielectric layer(s), areflective layer(s), and/or a protective layer, as well as combinationscomprising at least one of the foregoing layers. These layers compriseconventional materials and are disposed in accordance with the type ofmedia produced. For example, for a first surface media, the layers maybe protective layer, dielectric layer, data storage layer, dielectriclayer, and then the reflective layer disposed in contact with thesubstrate, with an optional decorative layer disposed on the oppositeside of the substrate. Meanwhile, for an optical media, the layers maybe optional decorative layer, protective layer, reflective layer,dielectric layer, and data storage layer, with a subsequent dielectriclayer in contact with the substrate. It is understood that the form ofthe media is not limited to disk-shape, but may be any shape which canbe accommodated in a readout device.

[0044] The data storage layer(s) may comprise any material capable ofstoring retrievable data, such as an optical layer, magnetic layer, or amagneto-optic layer. Typically the data layer has a thickness of up toabout 600 Angstroms (Å) or so, with a thickness up to about 300 Åpreferred. Possible data storage layers include, but are not limited to,oxides (such as silicone oxide), rare earth element—transition metalalloy, nickel, cobalt, chromium, tantalum, platinum, terbium,gadolinium, iron, boron, others, and alloys and combinations comprisingat least one of the foregoing, organic dye (e.g., cyanine orphthalocyanine type dyes), and inorganic phase change compounds (e.g.,TeSeSn, InAgSb, and the like).

[0045] The protective layer(s), which protect against dust, oils, andother contaminants, can have a thickness of greater than about 100microns (μ) to less than about 10 Å, with a thickness of about 300 Å orless preferred in some embodiments, and a thickness of about 100 Å orless especially preferred. The thickness of the protective layer(s) isusually determined, at least in part, by the type of read/writemechanism employed, e.g., magnetic, optic, or magneto-optic. Possibleprotective layers include anti-corrosive materials such as gold, silver,nitrides (e.g., silicon nitrides and aluminum nitrides, among others),carbides (e.g., silicon carbide and others), oxides (e.g., silicondioxide and others), polymeric materials (e.g., polyacrylates orpolycarbonates), carbon film (diamond, diamond-like carbon, and thelike), among others, and combinations comprising at least one of theforegoing.

[0046] The dielectric layer(s), which are disposed on one or both sidesof the data storage layer and are often employed as heat controllers,can typically have a thickness of up to or exceeding about 1,000 Å andas low as about 200 Å or less. Possible dielectric layers includenitrides (e.g., silicon nitride, aluminum nitride, and others); oxides(e.g., aluminum oxide); carbides (e.g., silicon carbide); andcombinations comprising at least one of the foregoing materials, amongother materials compatible within the environment and preferably notreactive with the surrounding layers.

[0047] The reflective layer(s) should have a sufficient thickness toreflect a sufficient amount of energy (e.g., light) to enable dataretrieval. Typically the reflective layer(s) can have a thickness of upto about 700 Å or so, with a thickness of about 300 Å to about 600 Ågenerally preferred. Possible reflective layers include any materialcapable of reflecting the particular energy field, including metals(e.g., aluminum, silver, gold, titanium, and alloys and mixturescomprising at least one of the foregoing metals, and others).

[0048] In addition to the data storage layer(s), dielectric layer(s),protective layer(s) and reflective layer(s), other layers can beemployed such as lubrication layer and others. Useful lubricants includefluoro compounds, especially fluoro oils and greases, and the like.

[0049] The following examples are provided to further illustrate thepresent invention and not to limit the scope hereof.

EXAMPLES

[0050] Colored pellets were prepared by mixing low viscositypolycarbonate resin powder (melt flow at 250° C. of 11 grams per 10minutes (ASTM-D1238); molecular weight of about 17,700 grams per mole(g/mol) measured on GPC) with colorants specified in the Table.Formulations also included mold release agent (0.02 wt % glycerolmonostearate) and Doverphos (S-9228);Bis(2,4-dicumylphenyl)pentaerythritol diphosphate antioxidant at 0.02 wt%). The blends were melted in a 30 millimeter (mm) twin-screw extruder,passed through a die, cooled, and pelletized.

[0051] Resulting pellets were injection molded into 1.2 mm thick compactdisk substrates using a Krauss Maffei 80/190° C. Marathon Series, CDLiner, w/Non-Open Mold. Processing conditions as follows: Barrel ZoneTemperature of about 250 to about 330° C.; Mold Temperatures set to 45°C.; Injection Speed Profile of about 20 millimeters per second (mm/s) toabout 65 mm/s, 4 stages; Holding Pressure profile of about 150 bar toabout 550 bar, 5 stages; Holding Pressure Time of about 0.05 to about0.25 seconds, 5 stages; Cooling Time set for 2.5 seconds; Clamp Tonnageset for 400 kN; Injection pressure set at 1795 bar; Injection PositionProfile of about 17.0 mm to about 4.5 mm, 4 stages. The resulting diskswere tested for Block Error Rate on a CD Associates SL100 opticaltester. Block Error Rate (BLER) is a measure of the number of blocks ofdata that have at least one occurrence of erroneous data. BLER is thecombination of E11+E21+E31+E12+E22+E32 errors. A Block Error Rate belowabout 220 pulses is typically required in industry, with below 100preferred, and below 50 especially preferred.

[0052] Pellets were also injection molded into 1.2 mm thick coloredsubstrate (disk) and placed in spectrophotometer to determine theabsorbance at 780 nanometers (nm), (i.e., the wavelength of the opticaldisk tester. If the disc is not readable by the tester an error messageis given such as: “Unable to Retrieve VTOC (1FB)”. Which means that thetester could not establish the “Volume Table of Contents”, thisinformation shows the layout of the program material on the disc. TABLELoading % TRM at Elect. Color Colorant (wt %) 780 nm Test BLER Clear — —95.0 Pass 6.2 lt. Orange R672: CI Solvent Orange 63 0.005 94.8 Pass 15.4fluorescent dk. Orange R65: C.I. Pigment Red 181 0.005 94.7 Pass 9.5fluorescent Magenta R663: Kenawax Fluorescent Red 3BYP 0.050 94.7 pass38.5 fluorescent Brightened lt. R73: C.I. Solvent Blue 97 R513: 0.000394.4 Pass 25.6 Blue 2.5 bis(5′-tert-butyl-2-benzoxazolyl) 0.008thiophene green/yellow R887: C.I. Solvent Green 0.100 94.6 Pass 13.7fluorescent Brightened lt. R882: C.I. Solvent Yellow 98R73: C.I. 0.0000794.7 Pass 31.2 Green Solvent Blue 97 0.0004 green purple AM190:ChromaFlair Green/Purple 190 0.110 67.9 fail gold silver AM080:ChromaFlair Gold/Silver 080 0.060 65.8 fail cyan purple AM230:ChromaFlair Cyan/Purple 230 0.100 65.3 fail Sandorin blue R7260: PigmentBlue 60 0.010 71.1 pass 64.1 Pink with glass R666: C.I. Solvent Red 207R203: 0.009 91.4 fail flake Carbon Black Monarch 800 R71: C.I. 0.000022Solvent Violet 13 R0979: Engelhard 0.00022 Mearl Pigment EP 97079 0.200Green with glass R203: Carbon Black Monarch 800 0.0000133 90.9 failflake R883: C.I. Pigment Yellow 138 0.00712 R36: Solvent Green 28 R0979:Engelhard Mean Pigment EP 97079 0.00329 0.200

[0053] An alternative technique for product differentiation, coloreddisks, however, have not been used for optical media substrates due toabsorption of the laser light, which interferes with data readout.Furthermore, the use of optical effects, such as fluorescence, inoptical media substrates has not been done because fluorescence, inwhich light of a given color is absorbed and re-emitted at a differentcolor, has not been tried because fluorescent emissions may interferewith the laser readout system. Other visual effects that may scatter anincident laser beam have similarly not been explored because, untilrecently, optical media consisted of 1-layer substrates, such as thosein CD. Recently, the advent of DVD includes a second substrate layerwhich may be used for decorative purposes except in cases of multi-sidedmedia. The use of inorganic fillers such as glass flake to producevisual effects may also alter rheological properties of a thermoplasticresin making it difficult to produce optical media substrates from suchcompositions.

[0054] Use of color or other visual effects in optical media substratesprovides a way to differentiate brands of optical media. Thisdifferentiation can be used for increased appeal in the market, brandrecognition, and can help avoid problems with unwanted duplication ofdata. Colored substrates can also provide an advantage of wavelengthselectivity that cannot be obtained with colorless materials.

[0055] Data storage media substrates comprising visual effects have notpreviously been produced due to the significant adverse effect onrheology imparted by the visual effects. Previously, decorative labelswould be glued to a surface of the substrate. In contrast, thesubstrates described herein can comprise the visual effects as part ofthe substrate, i.e., a molded layer disposed on one side of thesubstrate. Alternatively, the visual effects can be disposed between twosubstrates with reflective and data layers disposed between the visualeffects and the substrate, optionally, adhesives can be used forbonding. These visual effects could be employed for numerous purposesincluding product differentiation, decoration, anti-piracy, and thelike.

[0056] While preferred embodiments have been shown and described,various modifications and substitutions may be made thereto withoutdeparting from the spirit and scope of the invention. Accordingly, it isto be understood that the present invention has been described by way ofillustrations and not limitation.

1. A method for producing a data storage media, comprising: molding amaterial comprising plastic and colorant to form a substrate, whereinthe substrate has a transmissivity of about 70% to about 85% at areadback laser wavelength when traversing a 1.2 mm thick coloredsubstrate; disposing a data layer on the substrate.
 2. The method ofclaim 1, further comprising disposing a reflective layer on a side ofthe data layer opposite the substrate.
 3. The method of claim 2, furthercomprising disposing a dielectric layer between the data layer and thereflective layer.
 4. The method of claim 1, further comprising formingthe material by mixing polycarbonate with the colorant, and wherein themolding further comprises injection molding.
 5. The method of claim 1,further comprising disposing a protective layer on a side of the datalayer opposite the substrate, wherein the protective layer comprisespolycarbonate.
 6. The method of claim 5, wherein the plastic comprisespolyetherimide.
 7. The method of claim 1, wherein the transmissivity isabout 75% to about 80%.
 8. The method of claim 1, wherein thetransmissivity is about 75% to about 85%.
 9. A method for producing datastorage media, comprising: molding a material comprising plastic,colorant, and visual effects to form a substrate, wherein the substratehas a transmissivity of about 85% or less at a readback laser wavelengthwhen traversing a 1.2 mm thick colored substrate, and wherein the visualeffects are selected from the group consisting of glass, metal, titaniumdioxide, mica, angular metamerism materials, and combinations comprisingat least one of the foregoing visual effects; and disposing a data layeron the substrate.
 10. The method of claim 9, wherein the visual effectshave a geometry selected from the group consisting of chips, particles,and combinations comprising at least one of the foregoing geometries.11. The method of claim 9, wherein the visual effects are in the form offlakes.
 12. The method of claim 9, further comprising disposing areflective layer on a side of the data layer opposite the substrate. 13.The method of claim 12, further comprising disposing a dielectric layerbetween the data layer and the reflective layer.
 14. The method of claim9, further comprising disposing a protective layer on a side of the datalayer opposite the substrate, wherein the protective layer comprisespolycarbonate.
 15. The method of claim 14, wherein the plastic comprisespolyetherimide.
 16. A method for producing a data storage media,comprising: molding a material comprising plastic and a fluorescentmaterial to form a substrate, wherein the substrate has a transmissivityof about 85% or less at a readback laser wavelength when traversing a1.2 mm thick colored substrate, and wherein the has a fluorescent coloremission wavelength which is not equal to the readback laser wavelength;and disposing a data layer on the substrate.
 17. The method of claim 16,wherein the fluorescent color emission wavelength is different than thereadback laser wavelength by at least about ±10 nm.
 18. The method ofclaim 16, wherein the fluorescent color emission wavelength is differentthan the readback laser wavelength by at least about ±20 nm.
 19. Themethod of claim 16, further comprising disposing a reflective layer on aside of the data layer opposite the substrate.
 20. The method of claim19, further comprising disposing a dielectric layer between the datalayer and the reflective layer.
 21. The method of claim 16, furthercomprising disposing a protective layer on a side of the data layeropposite the substrate, wherein the protective layer comprisespolycarbonate.
 22. The method of claim 21, wherein the plastic comprisespolyetherimide.
 23. A method for producing a data storage media,comprising: molding a material comprising plastic, and a fluorescentmaterial to form a substrate, wherein the substrate has a transmissivityof about 85% or less at a readback laser wavelength when traversing a1.2 mm thick colored substrate, and wherein the substrate has afluorescent color emission wavelength which is not equal to the readbacklaser wavelength and has a transmissivity of about 70% to about 90% atthe laser readback wavelength.